In recent years, techniques have become known for using a power management apparatus (for example, a Home Energy Management System (HEMS)) provided for each consumer's facility to control the load established for the consumer's facility, the distributed power source established for the consumer's facility, and the like (see JP 2003-309928 A (PTL 1)).
As the distributed power source, it is thought that a power generation apparatus that generates power from natural energy, such as a photovoltaic power generation apparatus or the like, will be used. The power generation amount during power generation from natural energy can vary for a variety of reasons. In order for the power management apparatus to control other apparatuses, however, it may be necessary to predict the power generation amount. Therefore, it has been proposed to calculate a predicted value of the power generation amount by predicting the solar radiation intensity based on past solar radiation intensity, weather information, and the like and converting the predicted solar radiation intensity into a power generation amount by photovoltaic power generation (see JP 2005-086953 A (PTL 2)).